Package org.apache.heron.api.bolt

Class WindowedBoltExecutor

java.lang.Object

org.apache.heron.api.bolt.WindowedBoltExecutor

All Implemented Interfaces:

Serializable, IBolt, IRichBolt, IComponent, IStatefulComponent<Serializable,Serializable>

Direct Known Subclasses:

StatefulWindowedBoltExecutor

public class WindowedBoltExecutor
extends Object
implements IRichBolt, IStatefulComponent<Serializable,Serializable>

An IWindowedBolt wrapper that does the windowing of tuples.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
static String	LATE_TUPLE_FIELD
protected WaterMarkEventGenerator<Tuple>	waterMarkEventGenerator

Constructor Summary

Constructors

Constructor	Description
WindowedBoltExecutor(IWindowedBolt bolt)

Method Summary

Modifier and Type	Method	Description
protected void	boltExecute(List<Tuple> tuples, List<Tuple> newTuples, List<Tuple> expiredTuples, Long timestamp)
void	cleanup()	Called when an IBolt is going to be shutdown.
void	declareOutputFields(OutputFieldsDeclarer declarer)	Declare the output schema for all the streams of this topology.
protected void	doPrepare(Map<String,Object> topoConf, TopologyContext context, OutputCollector collector, Collection<Event<Tuple>> queue)
void	execute(Tuple input)	Process a single tuple of input.
Map<String,Object>	getComponentConfiguration()	Declare configuration specific to this component.
protected Map<String,Serializable>	getState()
protected int	getTopologyTimeoutMillis(Map<String,Object> topoConf)
void	initState(State<Serializable,Serializable> state)	Initializes the state of the function or operator to that of a previous checkpoint.
protected WindowLifecycleListener<Tuple>	newWindowLifecycleListener()
void	prepare(Map<String,Object> topoConf, TopologyContext context, OutputCollector collector)	Called when a task for this component is initialized within a worker on the cluster.
void	preSave(String checkpointId)	This is a hook for the component to perform some actions just before the framework saves its state.
protected void	start()	Start the trigger policy and waterMarkEventGenerator if set
protected void	validate(Map<String,Object> topoConf, BaseWindowedBolt.Count windowLengthCount, Long windowLengthDuration, BaseWindowedBolt.Count slidingIntervalCount, Long slidingIntervalDuration)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

LATE_TUPLE_FIELD

public static final String LATE_TUPLE_FIELD

See Also:

Constant Field Values

waterMarkEventGenerator

protected transient WaterMarkEventGenerator<Tuple> waterMarkEventGenerator

Constructor Detail

WindowedBoltExecutor

public WindowedBoltExecutor(IWindowedBolt bolt)

Method Detail

getTopologyTimeoutMillis

protected int getTopologyTimeoutMillis(Map<String,Object> topoConf)

validate

protected void validate(Map<String,Object> topoConf,
                        BaseWindowedBolt.Count windowLengthCount,
                        Long windowLengthDuration,
                        BaseWindowedBolt.Count slidingIntervalCount,
                        Long slidingIntervalDuration)

getState

protected Map<String,Serializable> getState()

start

protected void start()

Start the trigger policy and waterMarkEventGenerator if set

prepare

public void prepare(Map<String,Object> topoConf,
                    TopologyContext context,
                    OutputCollector collector)

Description copied from interface: IBolt

Called when a task for this component is initialized within a worker on the cluster. It provides the bolt with the environment in which the bolt executes.

This includes the:

Specified by:

prepare in interface IBolt

Parameters:

topoConf - The Heron configuration for this bolt. This is the configuration provided to the topology merged in with cluster configuration on this machine.

context - This object can be used to get information about this task's place within the topology, including the task id and component id of this task, input and output information, etc.

collector - The collector is used to emit tuples from this bolt. Tuples can be emitted at any time, including the prepare and cleanup methods. The collector is thread-safe and should be saved as an instance variable of this bolt object.

doPrepare

protected void doPrepare(Map<String,Object> topoConf,
                         TopologyContext context,
                         OutputCollector collector,
                         Collection<Event<Tuple>> queue)

execute

public void execute(Tuple input)

Description copied from interface: IBolt

Process a single tuple of input. The Tuple object contains metadata on it about which component/stream/task it came from. The values of the Tuple can be accessed using Tuple#getValue. The IBolt does not have to process the Tuple immediately. It is perfectly fine to hang onto a tuple and process it later (for instance, to do an aggregation or join).

Tuples should be emitted using the OutputCollector provided through the prepare method. It is required that all input tuples are acked or failed at some point using the OutputCollector. Otherwise, Heron will be unable to determine when tuples coming off the spouts have been completed.

For the common case of acking an input tuple at the end of the execute method, see IBasicBolt which automates this.

Specified by:

execute in interface IBolt

Parameters:

input - The input tuple to be processed.

cleanup

public void cleanup()

Description copied from interface: IBolt

Called when an IBolt is going to be shutdown. There is no guarentee that cleanup will be called, because the supervisor kill -9's worker processes on the cluster.

The one context where cleanup is guaranteed to be called is when a topology is killed when running Heron in simulator.

Specified by:

cleanup in interface IBolt

declareOutputFields

public void declareOutputFields(OutputFieldsDeclarer declarer)

Description copied from interface: IComponent

Declare the output schema for all the streams of this topology.

Specified by:

declareOutputFields in interface IComponent

Parameters:

declarer - this is used to declare output stream ids, output fields, and whether or not each output stream is a direct stream

getComponentConfiguration

public Map<String,Object> getComponentConfiguration()

Description copied from interface: IComponent

Declare configuration specific to this component. Only a subset of the "topology.*" configs can be overridden. The component configuration can be further overridden when constructing the topology using TopologyBuilder

Specified by:

getComponentConfiguration in interface IComponent

newWindowLifecycleListener

protected WindowLifecycleListener<Tuple> newWindowLifecycleListener()

boltExecute

protected void boltExecute(List<Tuple> tuples,
                           List<Tuple> newTuples,
                           List<Tuple> expiredTuples,
                           Long timestamp)

initState

public void initState(State<Serializable,Serializable> state)

Description copied from interface: IStatefulComponent

Initializes the state of the function or operator to that of a previous checkpoint. This method is invoked when a component is executed as part of a recovery run. In case there was prior state associated with the component, the state will be empty. Stateful Spouts/Bolts are expected to hold on to the state variable to save their internal state

Note that initialState() is called before open() or prepare().

Specified by:

initState in interface IStatefulComponent<Serializable,Serializable>

Parameters:

state - the previously saved state of the component.

preSave

public void preSave(String checkpointId)

Description copied from interface: IStatefulComponent

This is a hook for the component to perform some actions just before the framework saves its state.

Specified by:

preSave in interface IStatefulComponent<Serializable,Serializable>

Parameters:

checkpointId - the ID of the checkpoint